WO2013020912A1 - Préparation de microcristaux ou nanocristaux orientés induits par laser femtoseconde dans des verres - Google Patents

Préparation de microcristaux ou nanocristaux orientés induits par laser femtoseconde dans des verres Download PDF

Info

Publication number
WO2013020912A1
WO2013020912A1 PCT/EP2012/065239 EP2012065239W WO2013020912A1 WO 2013020912 A1 WO2013020912 A1 WO 2013020912A1 EP 2012065239 W EP2012065239 W EP 2012065239W WO 2013020912 A1 WO2013020912 A1 WO 2013020912A1
Authority
WO
WIPO (PCT)
Prior art keywords
writing
region
femtosecond laser
anyone
transparent matrix
Prior art date
Application number
PCT/EP2012/065239
Other languages
English (en)
Other versions
WO2013020912A9 (fr
Inventor
Bertrand Poumellec
Matthieu Jean-Pierre LANCRY
Chaxing FAN
Huidan ZENG
Original Assignee
Universite Paris Sud 11
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Universite Paris Sud 11 filed Critical Universite Paris Sud 11
Publication of WO2013020912A1 publication Critical patent/WO2013020912A1/fr
Publication of WO2013020912A9 publication Critical patent/WO2013020912A9/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C30B11/005—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method by irradiation or electric discharge
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B32/00—Thermal after-treatment of glass products not provided for in groups C03B19/00, C03B25/00 - C03B31/00 or C03B37/00, e.g. crystallisation, eliminating gas inclusions or other impurities; Hot-pressing vitrified, non-porous, shaped glass products
    • C03B32/02—Thermal crystallisation, e.g. for crystallising glass bodies into glass-ceramic articles
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
    • C03C10/0009—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing silica as main constituent
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C23/00—Other surface treatment of glass not in the form of fibres or filaments
    • C03C23/0005—Other surface treatment of glass not in the form of fibres or filaments by irradiation
    • C03C23/0025—Other surface treatment of glass not in the form of fibres or filaments by irradiation by a laser beam
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides
    • C30B29/22—Complex oxides
    • C30B29/30—Niobates; Vanadates; Tantalates
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/35—Non-linear optics
    • G02F1/355—Non-linear optics characterised by the materials used
    • G02F1/3551—Crystals
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2202/00—Materials and properties
    • G02F2202/20—LiNbO3, LiTaO3
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2202/00—Materials and properties
    • G02F2202/36—Micro- or nanomaterials

Definitions

  • the present invention concerns a method for producing monocrystalline region in the bulk of a transparent matrix including Si0 2 and Li 2 0 and Nb 2 0 5 .
  • This method comprises producing a precipitate of LiNb0 3 in at least one selected volumic unitary region, so-called target region, selectively determined within the bulk material of said transparent matrix, for example through known digitally driven electromechanical means, and selective irradiation by a femtosecond laser focused onto said unitary target region.
  • successive adjacent unitary target regions may furthermore be produced along a trajectory which is determined so as to be parallel or perpendicular to the c-axis direction of a given crystalline internal orientation.
  • the invention proposes to adjust pulse energy and/or polarization direction of the laser writing light in order to produce micro or nano crystals with c-axis parallel or perpendicular to the writing direction.
  • This method enables to produce various components, including optical gratings or arrays, waveguides and/or polarizers, which may include one or several polarizing gratings possibly having different photonic and/or geometry characteristics.
  • Composite materials containing nanoparticules or microcrystals have found an increasing number of applications in different fields of science and technology, such as in the various fields of optics and photonics components and devices.
  • nanostructured glassy materials are various, such as via reduction of metallic ions introduced in glasses during melting, via ion-exchange processes followed by laser processing of the glassy materials or by their thermal processing either in air or in a reducing atmosphere, via microwave-assisted diffusion, or via co-RF-sputtering of glass and metals as well as via introducing conductive carbon nanostructures into glasses during melting.
  • Variations of optical properties designed in such nano or microstructured composite materials may produce useful macroscopic effects, in a way that depends on the size, shape, distribution and orientation of the crystalline structure.
  • Orientation of a crystalline structure here refers to the specific arrangement of its atomic components, as defined in crystallography.
  • a crystal structure is composed of a motif, a set of atoms arranged in a particular way, and a lattice. The symmetry properties of the crystal are embodied in its point and space group.
  • the crystal structure and its symmetry play a role in determining many of its properties, such as cleavage directions, electronic band structure, and optical properties. They are thus important for controlling local non-linear properties.
  • crystalline continuity and uniformity is important in obtaining interesting effects at the macroscopic level, or even for obtaining any macroscopic effect at all.
  • polycrystalline non- centrosymmetric materials do not show piezoelectricity, pyroelectricity or non-linear optical properties, i.e. are not macroscopically anisotropic if the crystals are randomly oriented. Only in crystal oriented materials, pyro-, piezo-electricity or NLO properties may be observed . This means that c-axis of the crystal have all the same direction, and the same orientation within this direction, i.e. like an assembly of parallel arrows.
  • Such 2D surface layer could be used to fabricate certain optical components such as gratings or polarizers.
  • the planar LiNb03 crystalline patterns had its c-axis orientation along the laser scanning direction.
  • An object of the invention is to improve and widen the technical possibilities known in the prior art. Moreover, it is an object of the invention to propose a method for selectively producing spatially oriented crystallization within the bulk of various transparent matrix materials. Thus, the invention also aims to obtain better and more various performances, ranges and types of effects; inter alia for enabling more compatibilities or less complexity in the range of available materials and production processes.
  • the invention proposes a method for preparing composite materials containing nanoparticules or nano or microcrystals with controlled local optical properties, from transparent matrices.
  • said method comprises writing a transparent matrix including Si0 2 and Li 2 0 and Nb 2 0 5 , by producing a precipitate of LiNb0 3 in at least one volumic unitary region, so-called target region, selectively determined within the bulk material of said transparent matrix, through selective irradiation by at least one fast pulsed laser, such as a femtosecond laser, focused onto said unitary target region.
  • new materials may be used as transparent matrix, and crystal orientation may be controlled, e.g . according to the detailed effects that are looked for as well as for the precise characteristics of such effects.
  • Such monocrystal may be used for its photoelectric, pyroelectric, piezoelectric, photorefractive, and /or non linear properties, such as in opto-acoustic or photoelectric or non-linear domains.
  • LiNb0 3 has numerous advantages, such as having the highest non-linear coefficient, which is seven times higher than for Ba 2 TiSi 2 0 8 .
  • such method may comprises producing a given continuous region, so-called multipoint region, within the bulk material of the transparent matrix, through implementing a plurality of irradiating steps focused on a plurality of successive adjacent or intersecting unitary target regions within said multipoint region, such as through scanning said continuous region with the focused pulsed laser.
  • Irradiation of the first region of these successive target regions takes place during a few seconds, so as to produce a precipitated crystal, for example between 1 s and 10 s, or preferably between 2 s and 5 s.
  • Further successive irradiation of further target regions then maintains and propagates a growth front starting from this first precipitated crystal.
  • First irradiation thus acts as a nucleation step while further successive irradiations act as which then act as successive growth steps.
  • initial duration may also be extended to a range of 1 s to 60 s, or preferably 1 s to 30 s.
  • the invention thus enables to obtain a continuous region of precipitated crystals within the bulk of the glass, possibly constituting a non ordered and/or polycrystalline region, such as for producing an isotropic refraction index variation.
  • the invention propose the successive steps of irradiating steps to be implemented in a spatial and temporal succession determined so as to obtain a monocrystalline region in the given continuous multipoint region.
  • the invention thus also enables to obtain a continuous region of monocrystals within the bulk of the glass, such as for producing devices implementing anisotropy or second harmonic generation.
  • the invention also proposes that the successive adjacent unitary target regions are produced along a trajectory which is determined so as to be parallel to the c-axis direction of a given (i.e. wanted) crystalline internal orientation.
  • the writing trajectory is controlled so as to follow the direction and orientation that are wanted to be the c-axis direction and orientation.
  • precipitated monocrystals may be used for building components or devices for laser frequency multiplexing or multiplication, as well as acoustic surface waves devices, optical modulators, photoelectric cells, optical parametric oscillators, or photoelectric or opto-acoustic devices or components.
  • such a method may be implemented for writing a transparent matrix comprising the following components molar fractions proportions:
  • Si0 2 less than 34% or 35%
  • Li 2 0 and Nb 2 0 5 in equal quantities, or with a difference of less than 20%, or possibly 10%.
  • Preparation of the transparent matrix comprises the following steps:
  • writing process is then implemented with one or preferentially all of the following parameters for the femtosecond laser:
  • wavelength between 0.4pm to 1.2pm. and preferentially around or at 1.03pm.
  • wavelength may be extended up to 1.7pm, or preferably around or at 1.55pm.
  • numerical aperture may be extended up to 1.6, or preferably to 1.4.
  • the scanning (i.e. movement of the focus point) trajectory while writing a multipoint region may be adjusted according to the following rules.
  • the femtosecond laser focus point is controlled so as to obtain, for the successive unitary target regions within a multipoint region so-called continuous written region, a pulse repetition rate of larger than 200 kHz and a scanning speed so-called writing speed smaller than 150 micrometer/s.
  • at least one written polarizing array or grating is written with a period lower than one micrometer; and/or is entirely written within an area of less than 10 or even 5pm 2 ; and/or is written in a transparent matrix the dimensions of which range from 5 x 5 mm to 50 x 30 mm (possibly for a plurality of different arrays).
  • inventors established that the size and orientation of the produced crystals depends on the individual pulse energy, and on the direction of the laser light polarization relatively to the writing direction in the case of writing with a linear polarized laser light.
  • the femtosecond laser is operated so as to write with a linear polarization parallel to the writing direction and a pulse energy between 0.5 ⁇ and 1.5pJ or even 1.6pJ, in order to obtain nanocrystals, such as with a maximum dimension of less than one micrometer, with their c-axis perpendicular to the writing direction.
  • a pulse energy between 0.5 ⁇ and 1.5pJ or even 1.6pJ, in order to obtain nanocrystals, such as with a maximum dimension of less than one micrometer, with their c-axis perpendicular to the writing direction.
  • Such nanocrystals with second order properties are mainly located in the back part of the written trace relatively to the laser light propagation direction, which enables to adjust the position of the writing so as to obtain theses nanocrystals in a given wanted position.
  • the invention then proposes to operate the femtosecond laser with a pulse energy between 0.5 ⁇ and l. lpJ or even 1.4 ⁇ _ ⁇ , in order to obtain a majority (such as more than 75% in area) or a totality of nanocrystals, with their c-axis perpendicular to the writing direction, thus enhancing the second order optical properties.
  • the femtosecond laser is operated so as to write with a linear polarization parallel to the writing direction and a pulse energy between 1.2 ⁇ ] or 1.4 ⁇ ] and 2.5pJ or even 5pJ, in order to obtain microcrystals (such as with a maximum dimension of more than one micrometer) with their c-axis parallel to the writing direction.
  • microcrystals with parallel c-axis are mainly located in the front part of the written trace relatively to the laser light propagation direction, which enables to adjust the position of the writing so as to obtain theses nanocrystals in a given wanted position.
  • the invention proposes to operate the femtosecond laser is operated with a pulse energy between 1.5 ⁇ and 2.5 ⁇ or even 5 ⁇ . ⁇ , in order to obtain a majority (such as more than 75% in area)or a totality of microcrystals, with their c-axis parallel to the writing direction, thus enhancing the corresponding optical properties.
  • a majority such as more than 75% in area
  • a totality of microcrystals with their c-axis parallel to the writing direction, thus enhancing the corresponding optical properties.
  • e L v when writing with a linear polarization perpendicular to the writing direction (with e L v ), produced crystals appear to stay quite small even with pulse energy values higher that with the precedent writing polarization.
  • the femtosecond laser is operated so as to write with a linear polarization perpendicular to the writing direction and a pulse energy between 0.6pJ and 3pJ, and preferably between 0.6 ⁇ and 2.5pJ, in order to obtain a majority or totality of nanocrystals, such as with a maximum dimension of less than one or two micrometers.
  • Such nanocrystals then include, on a one hand, nanocrystals with a c-axis perpendicular to the writing direction (thus enabling second order optical properties of the written pattern) and, on a second hand, nanocrystals with a c-axis parallel to the writing direction.
  • the invention also proposes a method for producing a photonic component, comprising at least one step of writing a plurality of multipoint regions within a transparent matrix through a method with linear polarized laser light as exposed here above, in a pattern designed to produce at least one device implementing second order optical properties, such as a frequency doubler.
  • FIGURE 1 schematically represents an example of spatially selective irradiation of one target region in the bulk of a transparent matrix, according to the invention
  • FIGURE 2 is a perspective view schematically representing a writing operation according to the invention, comprising irradiation of one multipoint continuous region including several successive target regions, along a writing trajectory comprising two successive non parallel directions;
  • FIGURE 3 is a top view schematically representing an example of a array comprising several separated parallel lines, each being written as a multipoint continuous region according to the invention
  • FIGURE 4 is a perspective view schematically representing an example of a 3D array comprising several separated parallel planes, each being written as a succession of three adjacently superposed multipoint continuous linear regions, irradiated according to the invention;
  • FIGURE 5 is a perspective view schematically representing an example of a 3D component comprising two superposed levels including each two perpendicularly oriented 3D arrays similar to FIGURE 4;
  • FIGURE 6a to FIGURE 6b are scanning electron microscope (SEM) images and electron backscatter diffraction (EBSD) images of crystals obtained in the interaction volume from a second example;
  • FIGURE 7a to FIGURE 7b are scanning electron microscope (SEM) images and electron backscatter diffraction (EBSD) images of crystals obtained in the interaction volume from a third example;
  • FIGURE 8a to FIGURE 8b are graphical results of calculation of the temperature field and of the thermal gradient distribution under scanning according to an exemplary embodiment of the invention, and show respectively:
  • FIGURE 8a the whole temperature field
  • FIGURE 8b the temperature gradient contour on the temperature background, in the partial area of the square figured in FIGURE 8a;
  • FIGURE 9a and FIGURE 9b are SHG images taken with perpendicular polarizations 17px and 17py of a same area within an oriented monocrystal obtained through writing from second example (FIGURE 6);
  • FIGURE 10a is a group of three electron backscatter diffraction (EBSD) images of crystals obtained in the interaction volume from a fourth example, in an embodiment of the invention where writing is done with a linear laser light polarized parallel to the writing direction, with three different value of pulse energy;
  • EBSD electron backscatter diffraction
  • FIGURE 10b is a electron backscatter diffraction (EBSD) image of crystals obtained in the interaction volume from the fourth example, but through writing with a linear laser light polarized perpendicular to the writing direction;
  • EBSD electron backscatter diffraction
  • FIGURE 11 is a group of ten electron backscatter diffraction (EBSD) images of crystals obtained similarly to FIGURE 10a, with ten different value of pulse energy.
  • EBSD electron backscatter diffraction
  • a glass of formula was produced with the followings molar fractions:
  • FIGURE 1 schematically represents an example of selective irradiation of one target region 102 in the bulk of a transparent matrix 10 here called glass, according to the invention .
  • a femtosecond laser beam 111 is focused by an objective or a lens 112, into a cone beam 113 toward a focus point 114 located within the bulk of the matrix.
  • the method of the invention comprises writing this transparent matrix 10 including Si0 2 and Li 2 0 and Nb 2 0 5 , so as to produce a precipitate of LiNb0 3 in at least one selected volumic unitary region 102, so-called target region.
  • This target region is selectively determined within the bulk material of said transparent matrix, for example through known digitally driven electromechanical means, and selective irradiation by a femtosecond laser is focused onto said unitary target region.
  • Crystallization takes place at the interface between the two phases liquid-solid, from exterior toward interior, in a crystallized region 102.
  • a writing operation comprises irradiation of at least one multipoint continuous region 220 so- called multipoint region.
  • Irradiation of the first region of these successive target regions takes place during a few seconds, so as to produce a precipitated crystal, for example between 1 s and 10 s, or preferably between 2 s and 5 s.
  • this continuous multipoint region 220 is selectively and spatially "written" within the bulk material of the transparent matrix, through implementing
  • this continuous multipoint region 220 is scanned with the focused beam 113, 114 of a pulsed laser, such as femtosecond laser 11, along a writing trajectory 221 which can be of any 2D or 3D shape or design.
  • This scanning may be obtained for example by a movement of the laser 11 or its objective 12, or a movement of the matrix, in a relative "scanning movement" shown in FIGURE 1 by the cross of the arrow rear 12. may be In this example, this trajectory comprises two successive non parallel directions 221a and 221b.
  • the successive steps of irradiating steps are implemented in a spatial and temporal succession determined so as to obtain a monocrystalline region in the given continuous multipoint region, thus adjusting the displacement rate of the growth front along the writing trace.
  • the energy deposited by the laser has enough time between two subsequent pulses to diffuse and equilibrate with the glass matrix. This produces a repeated series of rapid heating and quenching and no accumulation of heat, which cannot sustain suitable crystallization temperatures. This is a reason why sufficient repetition rate has to be reached in order to maintain crystallization temperature a time long enough in the written region 220.
  • successive adjacent unitary target regions may furthermore be produced along a trajectory 221 which is determined so as to be parallel to the c-axis direction of a given (i.e. wanted) crystalline internal orientation, shown in the figures by the short arrows 104a to 104j within the circle showing the central circular section of the unitary target regions 102a to 102j.
  • the crystallization of glasses is dominated by two factors based on the theory of crystallization : nucleation frequency and growth rate.
  • the speed to transform the glass state into crystal is relevant from the kinetics and it is determined by two steps: the nucleation and the growth of the nuclei.
  • nucleation and the growth of the nuclei In order to induce a phase transformation, it needs a large free enthalpy difference between the two phases, some seeds (fluctuations of molecular arrangement) and an activation energy barrier (interface energy) small enough to be overcome by vibration energy.
  • the stability of the seeds is determined by two terms. The first one is the volumic enthalpy difference between glass and crystal organization. It is defined by the following expression in which L is the latent heat from glass to crystal :
  • V seed volume (assumed spherical here).
  • the second one is the interface energy ⁇ 5 ⁇ , which is positive. This one has to be multiplied by the surface of the seeds, and thus the total seed enthalpy depends on its radius and experience a maximum for a critical radius.
  • Possibilities to orient the crystallization arise from anisotropy in the free enthalpy expression on one hand, and from gradients in kinetics on the other hand [10] .
  • the minimum of enthalpy and the maximum in kinetics according to the orientation will favour crystallization in this orientation.
  • the enthalpy in each unitary target region depends on space and time coordinates.
  • the orientation for which the enthalpy decreases the fastest i.e. for which the kinetics is fastest
  • nucleation and growth involve atom migrations. These diffusions are driven, on one hand by the gradient of free enthalpy (i.e. gradients of chemical potentials, gradient of concentrations), of electric potential, or of stress but also by gradient of mobility that can be produced by temperature or light intensity gradient.
  • the particle formation is achieved in a space configuration 102 centered on the focus 104 of the beam.
  • the temperature gradient is oriented towards the focus center. Without other forces, such as in the first target region 102a, the orientation for the maximum crystallization rate is thus towards the center.
  • the temperature field departs from circularity and left a larger heated region and a weaker gradient field behind the spot than in front of it, as illustrated in region 1 of FIGURE 8. All the points situated in front of the spot will be heated and thus even if they have crossed the nucleation area, they will forget this period of time because they will be heated at higher temperature.
  • thermal gradient is oriented differently inside the line than outside and this is detrimental for uniform orientation.
  • moderating the energy deposition it is possible to write thinner lines uniformly oriented. This may explain some of the difficulties of adjusting the writing parameters.
  • the beam scanning movement modifies the previous radial geometry into a plane one.
  • crystallization is achieved in a very large temperature gradient that has a plane geometry with a gradient perpendicular to it and to the direction of scanning 221.
  • ferro-electric crystal By producing ferro-electric crystal with a femtosecond laser, the inventors showed that when they changed the orientation of scanning, the crystal orientation changed at the same time. In addition, they also showed that instead of producing an abrupt grain boundary to accommodate the change, the lattice orientation changed gradually, probably thanks to lattice strain, preserving a continuity between crystals differently oriented .
  • crystallization is sensitive to temperature gradient and it will be defined by the orientation of the laser scanning movement in the glass.
  • the orientation of the growth takes place during the step of writing the further target regions 102b to 102j, after nucleation in static mode in the first target region 102a. Therefore, as shown above, the particle nucleation is achieved in a space configuration centred on the focus for a static beam.
  • FIGURE 8a and FIGURE 8b shows the results of calculation of the temperature field and of the thermal gradient distribution under scanning for the glass 0.6(Li 2 O. Nb 2 O5)-0.4SiO2, for pulse energy of 1.5 ⁇ -1/pulse, scanning speed of 100 ⁇ /s toward the right hand side.
  • FIGURE 8a shows the whole T field, with the elliptical shape of the isotherms.
  • the temperature range around 750 K should be considered adapted for producing growth (light blue).
  • the black square marks the location of the results shown in FIGURE 8b.
  • FIGURE 8b displays the temperature gradient contour, in lines above the temperature background.
  • the large gradients are concentrated on the front of the beam. Note that the gradient in the growth zone is around 20 ⁇ / ⁇ in region 1 to 40 ⁇ / ⁇ in region 2, i.e. much smaller than that in static mode.
  • thermal diffusion and heat accumulation effects play an important role in forming crystals in glasses; and adjusting such parameters is relevant for the fabrication oriented crystals within such glasses.
  • a nucleation at the crystal growth front should be avoided for obtaining homogeneous crystal lines or regions 220, and moreover for obtaining regions 220 with oriented 104 crystals.
  • the invention makes it possible to use femtosecond laser to orient the crystals along a preferred direction in glasses by choosing suitable glass-matrices and accurately adjusting its parameters.
  • a most innovative aspect of the invention is that it will be possible to grow the microcrystals in a selected direction or orientation in the bulk and not at the surface only.
  • microcrystals directly by controlling the scanning movement of the laser (and of its focus).
  • Such flexibility of the pattern design may also enable to shape nonlinear optical properties in more various forms, e.g. for obtaining second and third order non linear susceptibility.
  • writing may be obtained with little or no surface damage on the matrix. More generally, spatial selectivity through laser scanning control and various possibilities of parameters such as wavelength, numerical aperture, pulse energy, polarization direction, but also spatio-temporal pulse shaping and writing direction, makes this process a very flexible tool for a versatile and easy to set up production.
  • Short pulse duration allows applying a very large light intensity (more than TW/cm 2 ) in delivering a rather small quantity of energy (smaller than a few 10s ⁇ -l/pulse).
  • femtosecond laser direct writing technique allows thus 3D engineering of the optical properties of the material via gaining control over the 3D spatial distribution of nanocrystals in the glass down to sub-micrometer scale. This presents interesting prospects for shaping novel 3D photonic structures for optical telecommunication applications, high power laser and so more.
  • the invention enables producing new structures in 3D and new original devices based on nanocrystals embedded within glass matrix, in either polycrystalline or oriented monocrystalline traces.
  • Polycrystalline traces may be used for example for producing various 3D volumic devices, for example of a kind that uses isotropic refraction index variation, such as waveguides or optical diffractive devices.
  • Monocrystalline traces may be used for producing various 3D volumic devices, for example of the kind using anisotropy or second harmonic generation, such as for converting Infra Red light into visible light.
  • devices such as polarizer, diffractive optics, waveguides, sensors, frequency doubling devices, photonic crystals and even metamaterials (i.e. ordered composites) can be developed.
  • Such components could enable to be implemented in various fields and under various forms, such as integrated-optics, nano-optics, optical components, optoelectronics or bio-photonics.
  • the design of the nano or micro structured material is optimized in terms of spatial distribution, concentration, size, shape and orientation of the nanocrystals.
  • the variability of the final product may be adjusted based on this optimization.
  • the invention thus also proposes to produce a polarizing component through writing a method according to method here above within at least one transparent matrix.
  • a polarizing component may be or include a polarizing grating 3 produced by writing in an essentially 2D (plane) matrix 30 a plurality of multipoint regions 321 to 327 through a method as exposed here above, in a pattern designed to produce at least one polarizing array 32.
  • such a component may be a 3D polarizer 4 produced by writing within a thick volumic matrix 40 a plurality of parallel "planes" 421 to 427 forming a 3D array 42, each plane being obtained by writing a plurality of superposed adjacent or intersecting multipoint regions 421a to 421c.
  • Method according to the invention may further comprises writing within the at least one transparent matrix (and possibly a single matrix) a plurality of polarizing arrays having different photonic and/or geometry characteristics.
  • a single monolithic volumic matrix 50 is written with four 3D arrays 51 to 54 spread on different levels 50a and 50b, and having two perpendicular orientations on each level.
  • FIGURE 6a Another exemplary implementation of the invention is detailed hereunder in a non limitative way, related to FIGURE 6a and FIGURE 6b.
  • a glass was produced with the molar fractions formula : 34Si0 2 -33Li 2 0-33Nb 2 0 5 (mol%).
  • Main raw materials are 7.14g of quartz sand, 13.44g of lithium carbonate and 30.73g of niobium oxide. These components were mixed and grinded to a homogeneous composition. This mix was put in a quartz or platinum crucible which was then kept in an oven for 2h at 1400°C, so as for the components to be melted and dispersed in an homogeneous way. This crucible was taken out, and melted mix was cast in a preheated mold to produce glass. This glass was then slowly cooled in another oven, through an annealing process of 12h from 550°C to room temperature. Glass was then cut and polished to produce transparent (pale yellow) samples. For the writing, the beam of the femtosecond laser was focused in a point spatially selected within the bulk of the glass, and further scanning movements along vector k may be obtained through software control of the motorized laser tray.
  • FIGURE 6a and FIGURE 6b show written crystals from example 2, through scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) images.
  • FIGURE 6a image shows a lenticular trace of the laser, with maximal width and length of respectively lOprn and 30pm.
  • FIGURE 6b shows the distribution of crystal orientation in the laser irradiated area 620. In the middle region 604 of this area, we can see that the crystal is sensibly parallel to the c(0001) axis, which is often the most important for many properties. Coordinates of orientations are shown in the nearby triangle, where different orientations are figured by different shades (originally in colors).
  • k is the direction of the laser radiation propagation.
  • FIGURE 7a and FIGURE 7b show crystals from example 2, through scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) images.
  • FIGURE 7a image shows a lenticular trace of the laser under scanning, with maximal width and length of respectively 9pm and 18pm.
  • FIGURE 7b shows the distribution of crystal orientation in the laser irradiated area 720.
  • a homogeneous region 704 can be seen in the middle of this area, in which the crystal orientation is parallel to a direction D704 situated between the c (0001) axis and the 1100 direction.
  • FIGURE 9a and FIGURE 9b are two second harmonic generation (SHG) images, which demonstrate the monocrystalline properties and the unicity of orientation of the polar axis direction of the written trace. These two images are taken under different polarizations 17px and 17py, enlightened at 1.030 nm and read at 515 nm.
  • SHG second harmonic generation
  • Image FIGURE 9b show a far more visible pattern than FIGURE 9a, thus showing that polar axis orientation of the crystal is actually parallel to the polarization 17py, and thus parallel to the writing direction k .
  • FIGURE 10 Various possibilities of adjusting writing parameter, combining pulse energy and/or polarization direction of linear polarized writing light, are illustrated as a fourth example in FIGURE 10 and FIGURE 11, implemented with the same matrix as in example 2.
  • v is the direction of focus point displacement, while e pertains to the polarization direction.
  • FIGURE 10a In FIGURE 10a are shown electron backscatter diffraction (EBSD) images of crystals obtained in the interaction volume, writing with a linear laser light polarized parallel to the writing direction ( e // v ) .
  • the three images correspond to three different traces obtained with three different values of pulse energy, namely: 0.6pJ on the left, 1.5pJ in the centre, and 2.0pJ on the right of the figure.
  • Crystals obtained with a 0.6pJ pulse energy on the left image clearly present dimensions under 1 pm, and mostly under 0.5 or even 0.2 pm. Crystals obtained with a 1.5pJ and a 2.0pJ pulse energy show dimensions over lpm and mostly over 3pm.
  • FIGURE 11 are also shown electron backscatter diffraction (EBSD) images of crystals obtained in the interaction volume, still writing with a linear laser light polarized parallel to the writing direction ( e // v ) .
  • the ten images referenced from “a” to “j” correspond to ten different traces obtained with ten different values of pulse energy, namely from “a” to “j”: with respectively 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.8 and 0.6pJ.
  • FIGURE 10a and 11 for pulse energy under 1.1 pJ. a high majority or totality of produced crystals present a green or blue color, meaning that the c-axis orientation is perpendicular to the direction of the writing laser propagation.
  • images of FIGURE 10a and 11 show that writing with a linear laser light, with polarization parallel to writing direction, produces:
  • Sample of FIGURE 10b was obtained through writing with a linear laser light polarized perpendicular to the writing direction, with a pulse energy of 2.0pJ. It may be noted that similar images were obtained through writing with same polarization and a pulse energy of 1.8pJ, 2.2pJ and 2.45pJ.
  • FIGURE 10b a part of produced crystals presents blue, green or yellow color, while another part of produced crystals presents violet, orange or red color. It means that such laser light with polarization perpendicular to writing direction (with e L v ) may also be used for producing crystals that are oriented with c-axis perpendicular to the writing direction. Further test showed that these samples actually produce second order optical properties.
  • FIGURE 10b also shows that writing with linear laser light with polarization oriented perpendicular to the writing direction (with e L v ) produces small or average crystals, here under 3pm and mostly under lpm, even with a higher pulse energy (here of 2.0pJ). Comparatively, under laser light polarization parallel to the writing direction ( e // v ), similar size of crystals is obtained with lower pulse energy, such as with 0.8 to 1.3pJ in FIGURE 11.
  • writing with a linear laser light with polarization perpendicular to the writing direction may also be used for producing smaller or nanocrystals with a wider range of pulse energy, thus enabling less constraints and more flexibility in the process design and tuning, such as enabling writing wider traces or multipoint regions.
  • writing with a linear laser light with polarization perpendicular to the writing direction may also be used for producing smaller or nanocrystals with a c-axis parallel to the writing direction.
  • e // v under laser light polarization parallel to the writing direction ( e // v ), similar orientation of crystals is obtained with larger crystals, mostly microcrystals, such as with in FIGURE 6, FIGURE 7 and FIGURE 10a.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Nonlinear Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Optics & Photonics (AREA)
  • Metallurgy (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Ceramic Engineering (AREA)
  • Toxicology (AREA)
  • Health & Medical Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Thermal Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Dispersion Chemistry (AREA)
  • Laser Beam Processing (AREA)

Abstract

La présente invention concerne un procédé pour produire une région monocristalline dans la masse d'une matrice transparente comprenant du SiO2, du Li2O et du Nb2O5. Ce procédé consiste à produire un précipité de LiNbO3 dans au moins une région unitaire volumique sélectionnée, appelée région cible, sélectivement déterminée à l'intérieur du matériau de masse de ladite matrice transparente, par exemple à l'aide de moyens électromécaniques commandés par voie numérique, et à procéder à une irradiation sélective par un laser femtoseconde focalisé sur ladite région cible unitaire. Selon l'invention, des régions cibles unitaires adjacentes successives peuvent également être produites le long d'une trajectoire qui est déterminée afin d'être parallèle ou perpendiculaire à la direction de l'axe c d'une orientation interne cristalline donnée. Dans plusieurs modes de réalisation, l'invention propose d'ajuster l'énergie d'impulsion et/ou la direction de polarisation de la lumière d'écriture laser afin de produire des micro ou nanocristaux avec l'axe c parallèle ou perpendiculaire à la direction d'écriture. Ce procédé permet de produire divers composants, notamment des réseaux ou matrices optiques, des guides d'ondes et/ou des polariseurs, qui peuvent comprendre un ou plusieurs réseaux polarisants possédant éventuellement différentes caractéristiques photoniques et/ou géométriques.
PCT/EP2012/065239 2011-08-05 2012-08-03 Préparation de microcristaux ou nanocristaux orientés induits par laser femtoseconde dans des verres WO2013020912A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
PCT/IB2011/002076 WO2013021227A1 (fr) 2011-08-05 2011-08-05 Préparation de cristaux orientés induits par laser femtoseconde dans des verres
IBPCT/IB2011/002076 2011-08-05

Publications (2)

Publication Number Publication Date
WO2013020912A1 true WO2013020912A1 (fr) 2013-02-14
WO2013020912A9 WO2013020912A9 (fr) 2013-05-30

Family

ID=46754948

Family Applications (2)

Application Number Title Priority Date Filing Date
PCT/IB2011/002076 WO2013021227A1 (fr) 2011-08-05 2011-08-05 Préparation de cristaux orientés induits par laser femtoseconde dans des verres
PCT/EP2012/065239 WO2013020912A1 (fr) 2011-08-05 2012-08-03 Préparation de microcristaux ou nanocristaux orientés induits par laser femtoseconde dans des verres

Family Applications Before (1)

Application Number Title Priority Date Filing Date
PCT/IB2011/002076 WO2013021227A1 (fr) 2011-08-05 2011-08-05 Préparation de cristaux orientés induits par laser femtoseconde dans des verres

Country Status (1)

Country Link
WO (2) WO2013021227A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019208582A1 (fr) * 2018-04-26 2019-10-31 住友電気工業株式会社 Dispositif optique de conversion de longueur d'onde et procédé fabrication de dispositif optique de conversion de longueur d'onde
US11126064B2 (en) * 2019-01-09 2021-09-21 Sumitomo Electric Industries, Ltd. Optical wavelength conversion device

Non-Patent Citations (9)

* Cited by examiner, † Cited by third party
Title
"Femtosecond laser-induced oriented precipitation of Ba2TiGe208 crystals in glass", OPTICS EXPRESS, vol. 16, 2008, pages 3912 - 3917
A. STONE ET AL., OPTIC EXPRESS, vol. 17, 2009, pages 23284 - 23289
CHAXING FAN ET AL: "Three-dimensional photoprecipitation of oriented LiNbO_3-like crystals in silica-based glass with femtosecond laser irradiation", OPTICS LETTERS, vol. 37, no. 14, 15 July 2012 (2012-07-15), pages 2955, XP055039159, ISSN: 0146-9592, DOI: 10.1364/OL.37.002955 *
CHAXING FAN: "Directional Writing Dependence of Birefringence in Multicomponent Silica-based Glasses with Ultrashort Laser Irradiation", JOURNAL OF LASER MICRO NANOENGINEERING, vol. 6, no. 2, 1 September 2011 (2011-09-01), pages 158 - 163, XP055039162, DOI: 10.2961/jlmn.2011.02.0011 *
DATABASE COMPENDEX [online] ENGINEERING INFORMATION, INC., NEW YORK, NY, US; July 2004 (2004-07-01), JIANG X-W ET AL: "Femtosecond laser induced growth of LiNbO3 crystal in glass", XP002672555, Database accession no. E2004488687241 *
JOURNAL OF INORGANIC MATERIALS, vol. 19, no. 4, July 2004 (2004-07-01), pages 935 - 938, XP002672557 *
OPTICS EXPRESS., vol. 18, 2010, pages 8019 - 8024
VENKATARAMAN B ET AL: "Optical diffraction of second-harmonic signals in the LiBO2-Nb2O5 glasses induced by self-organized LiNbO3 crystallites", APPLIED PHYSICS LETTERS, AIP, AMERICAN INSTITUTE OF PHYSICS, MELVILLE, NY, US, vol. 87, no. 9, 25 August 2005 (2005-08-25), pages 91113 - 091113, XP012077599, ISSN: 0003-6951, DOI: 10.1063/1.2037198 *
YONESAKI Y ET AL: "Space-selective precipitation of non-linear optical crystals inside silicate glasses using near-infrared femtosecond laser", JOURNAL OF NON-CRYSTALLINE SOLIDS, NORTH-HOLLAND PHYSICS PUBLISHING. AMSTERDAM, NL, vol. 351, no. 10-11, 15 April 2005 (2005-04-15), pages 885 - 892, XP027660747, ISSN: 0022-3093, [retrieved on 20050415] *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019208582A1 (fr) * 2018-04-26 2019-10-31 住友電気工業株式会社 Dispositif optique de conversion de longueur d'onde et procédé fabrication de dispositif optique de conversion de longueur d'onde
US11126064B2 (en) * 2019-01-09 2021-09-21 Sumitomo Electric Industries, Ltd. Optical wavelength conversion device

Also Published As

Publication number Publication date
WO2013020912A9 (fr) 2013-05-30
WO2013021227A1 (fr) 2013-02-14

Similar Documents

Publication Publication Date Title
Zhang et al. Single femtosecond laser beam induced nanogratings in transparent media-Mechanisms and applications
Honma et al. Technique for writing of nonlinear optical single-crystal lines in glass
Lipatiev et al. Direct laser writing of LaBGeO5 crystal-in-glass waveguide enabling frequency conversion
Ogawa et al. Birefringence imaging and orientation of laser patterned β-BaB2O4 crystals with bending and curved shapes in glass
Gupta et al. Creation of Ferroelectric, Single‐Crystal Architecture in Sm0. 5La0. 5BGeO5 Glass
Andrushchak et al. Study of second harmonic generation in KDP/Al₂O₃ crystalline nanocomposite
WO2013020912A9 (fr) Préparation de microcristaux ou nanocristaux orientés induits par laser femtoseconde dans des verres
Kadan et al. Single-pulse femtosecond laser fabrication of concave microlens-and micromirror arrays in chalcohalide glass
Xiao et al. Preparation of crystalline beta barium borate (β‐BaB2O4) thin films by pulsed laser deposition
Lipat’ev et al. Specifics of the crystallization of lanthanum borogermanate glass by a femtosecond laser beam
Suzuki et al. Direct Laser Patterning of β‐BaB 2 O 4 Crystals with High Orientation in the Inside of Glass Fiber
US5127982A (en) Polycrystal piezoelectric device and method of producing the same
Sun et al. Abnormal elemental redistribution in oxyfluoride glasses induced by high repetition rate femtosecond laser
Fedotov et al. Local formation of birefringent structures in alkali-silicate glass by femtosecond laser beam
Lipat’ev et al. Early stages of crystallization of lanthanum-borogermanate glass by a femtosecond laser beam
CN102162132A (zh) 利用飞秒激光在玻璃内部诱导析出取向可控的铌酸锂单晶的方法
Kulyk et al. Nonlinear optical response of KDP/Al 2 O 3 crystalline nanocomposite
Liu et al. Femtosecond laser direct writing of TiO 2 crystalline patterns in glass
WO2014201672A1 (fr) Composé de li4sr(bo3)2, cristal de li4sr(bo3)2 à propriétés optiques non linéaires, procédé de fabrication s'y rapportant et ses utilisations
RU2640603C1 (ru) Способ получения конвертера поляризации
Liebig et al. Femtosecond laser precipitation of non-centrosymmetric crystals in glasses
Sergeev et al. Reversible phase–structure modification of photostructurable glass ceramic by CO 2 laser irradiation
Lotarev et al. Crystalline line formation from lithium heptagermanate in lithium germanate glass
Liebig et al. Femtosecond laser writing of electro-optic crystalline structures in glass
Xuan et al. Space-Selective Control of Functional Crystals by Femtosecond Laser: a Comparison Between SrO-TiO2-SiO2 and Li2O-Nb2O5-SiO2 Glasses

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 12751460

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 12751460

Country of ref document: EP

Kind code of ref document: A1